OBJECTIVE: The objective of this study was to determine if improved articulatory function was possible in glossectomized patients following prosthetic augmentation of the palatal vault. APPROAC: Two female patients served as the subjects of this study. In each case the left half of the patient's tongue and portions of the mandible, maxilla and palatal vault on the left side had been excised due to cancer. Each patient had an oral prosthesis constructed for her which conformed to the original palatal vault. A custom augmenting piece was also formed which could be attached to the palatal surface of each individual's prothesis. Two thin pseudopalates less than a half millimeter thick and containing 96 contact sensors were also made which fit the patient's prostheses; one conformed to the original palatal vault shape and the other to the augmented palatal contour. Stimulus materials consisted of two lingual fricatives combined with three point vowels to form symmetric syllables. Each syllable was repeated in a random sequence within a frame sentence. Acoustic an dynamic palatometric data were collected with a computerized system on three different days: Day 1, baseline using the unaugmented prothesis; Day 2, an A-B-A experiment where B was the unaugmented prothesis; and Day 3, one month after the augmented prosthesis had been worn daily. RESULTS: The dynamic palatometry data indicated that the augmented prosthesis enabled these patients to effect a significant difference in minimal groove formation not possible wih the unaugmented palate. An analysis-by-synthesis procedure used to evaluate the resulting acoustic spectra proved helpful in subsequent refining of the augmented prostheses. These results demonstrate the usefulness of prosthetic augmentation in improving the articulation of glossectomized patients.